Coring apparatus



March 16, 1943.

w. J. CRITEI'S conme APPARATUS Fil'ed llarch 24, 1941 Z SheetS-ShQBt 2FIG. 3

INVENTOR V w. J. canes 71min Patented Mar. 16, 1943 CORING APPARATUSWilbur J. Crites, Bartlesville, Okla, assignor to Phillips PetroleumCompany, a corporation of Delaware Application March 24, 1941, SerialNo. 385,016

Claims.

This invention relates to coring and more particularly to apparatus forobtainingrepresentative cores from subsurface formations.

It is common practice in the petroleum industry to obtain cores fromhydrocarbon-bearin formations for the purpose of determining certainreservoir characteristics which are useful in predicting reservoir fluidperformance. ,Vir-

gin reservoirsmay be bored usually with a relatively high percentage ofcore recovery. Depleted formations at shallow depths may be,

cored with equal success. on the other hand. coring depleted reservoirsat greater depths yields a relatively low percentage of core recovcry.in the present practice of coring, a drilling fluid is usuallycirculated downwardly throug the drill pipe and thence upwardly throughthe annular space between the bore hole and the unconsolidated formationis cored, drilling fluid un'der considerable pressure will wash awaycertain portions of the core so that that which remains isnon-representative of the formation cored. If a consolidated formationis cored, the drilling fluid will penetrate the core, contaminating theformation fluid therein. Nonrepresentative or contaminated cores havelittle or no value for analytical interpretation.

By the practice of my invention 1 am able to obtain representativeformation cores, which are not contaminated by drilling fluid. Theinven-, tion is especially useful in coring low pressure andnon-consolidated formations, as the pressure of the drilling fluid onthe face of the formation is approximately that of the formation. When aconstant load is carried on the core bit,

' therotational speed of the bit is inversely'proportional and thedeveloped torque is directly proportional to the hardness of theformation being cored.

It is the primary object of my, invention to obtain representative coresfrom subsurface formations.

Another object of my invention is the provision of apparatus forobtaining representative cores from low pressure and non-consolidatedformations.

A further object ofmy invention is the provision of apparatusforobtaining subsurface formation cores which are not contaminated withdrilling fluid.

These and additional objects and advantages will be apparent to personsskilled in the art by reference to the following description and annexeddrawings, wherein-- Figure 1 is an elevation view. of one embodiment ofmy invention, partly in cross section;

. Figure 2 is an elevation view of a second em.- bodiment ofmyinvention, partly in'cross section; Y

Figure 3 is an enlarged horizontal cross section view of the drivingmechanism, taken along the line 3-3 of Figure l, and;

Figure 4 is a sectional view of the driving mechanism, taken along theline 4-4 of Figure 3.

Referring to Figure 1, I have shown a casing III which extendsdownwardly in a bore hole II from the surface of the ground (not shown).A drill stem I2 is suspended and rotated within casing I0 in a wellknown manner from the surface of the ground. It will be noted from the afluid supply chamber I5, a differential drive --mechanism I6, an annularspace I1, an inner core barrel I8, and a core bit I9. The upper part ofbit I9 is grooved to receive the lower portion of drill stem I2 in sucha manner that the drill stem is free to rotate irrespective of therotation of the bit. A fluid, such as an oil,

which is used in operating my device, cools and lubricates the bit andcarries away the formation cuttings made thereby.

Chamber I 4 is formed by a cylindrical wall 20, whichis a portion of thedrill stem, intermediate a plug 2| and a filtering element 22 which arepositioned within the drill stem and ,provide the top and bottom,respectively, of the chamber.

The upper part of wall 20 has openings 23 which" v of the core barrel.

valve and perforations provides a means for disrotary pump 25which'serves .as' a fluid transmission or driving means. Any type ofpositive displacement rotary pump may be employed in the practice of myinvention. It is to be noted that the rotary ump 25 is positioned in andsecured to drill pipe l2 by means of an outer housing 26. An innerpartition 21, which allows communication between the rotary pump 'and isupply-chamber l through an inlet 28 and with annular space I! through arestricted outlet 29,

of smaller diameter than inlet 28, contains an idler gear 30 whichrotates on a fixed idler pin 3| and meshes with a rotor 32. The rotor,which is secured to a shaft 33, also rotates within the inner partition,and cooperates with the idler to' pump fluid from inlet 28 throughoutlet 29. A fixed crescent-shaped member 34 is positioned between therotor and the idler. Fluid from within the pump is prevented fromleaking out around shaft 33 by a packing gland 35 which is placed inthe'lower portion of housing 26.

Referring again to Figure 1, it will be noted that shaft 33 is securedto inner core barrel I8. The inner core barrel is threadedly attached tobit l9 and contains a check valve 36, which is positioned near the upperend of the core barrel, and one or more perforations 31, which areprovided between the valve and the upper end This arrangement of the ingmeans or core catcher 38 which allows the core, which is cutfrom aformation by the bit, to enter core barrel I8 through a passage 39therein during the coring operation. When the coring assembly is beingremoved from the well bore, the retaining means holds the core in thecore barrel. In addition to a central core 'passage 39, bit I!) isprovided with a plurality of fluid passages 40 which allow fluid fromannular space I! to lubricate and cool the bit and to carry awayformation cuttings which are chipped from the formation during thecoring operation by a plurality of cutters 4|. It is to be noted thatthe bit contains a packing element 42 at the base of drill stem |2,which prevents. leakage of the fluid around the base of the drill stem.

In the operation of this embodiment of my invention, the assembly shownin Figure 1 is lowered into bore hole II in the usual manner from hesurface -of the ground. A predetermined amount of circulating oil isinjected into annular space 24 until the hydrostatic head of the oil issubstantially equal to the formation pressure. In reservoirs where myinvention may be practiced, the formation pressure is generallysuflicient to .allow the oil to fill chambers l4 and I5, annular space[1, and annular space 24 to a point above openings 23 in the receivingchamber. The normal circulation of the oil through the apparatus may bethought of asstarting in supply chamber l5-from which it enters inlet 28of pump 25 and is pumped through outlet 29 into annular space II. Theoil leaves the annular space flowing through passages 40 in hit l9 tolubricate and cool the. bit. The oil entrains cuttings made by the bitand travels upwardly in annular space 24 entering receiving chamber I4through openings 23. Filtering element 22 separates the circulating oilfrom the cuttings, retaining the cuttings above the filter and allowingthe oil to pass downwardly into supply chamber 15 from which it may berecirculated.

. 'It will be noted the circulation is maintained 4 pumped and a torquewill be developed in the pump which is sufficient to overcome the loadon the bit and cause it to turn in the same direction as the drill pipe,but at a slower speed. As long as the weight on .the bitremainsconstant, the

differential speed between the bit and the drill pipe and a constantrate of circulation will be maintained. Further, unless there is aresistance to turning of bit l9, it will rotate at substantially thesame speed as drill pipe 12, however, under this condition, no fluidwill be transmitted through pump 2-5. This is the case when the drillpipe is held off the bottom of bore hole II. On the other hand, if bit19 is prevented from turning while drill pipe l2 rotates at a constantspeed, a maximum torque is developed and a maximum rate of circulationis obtained. This is analogous to setting full weight on the bit Whilecoring an extremely hard. formation and thus preventing rotation of thebit. The available torque for rotating the bit actually is the torquedeveloped in pumping oil through pump 25, as bit I9 is directlyconnected to the pump rotor by core barrel [8 and shaft 33. A torque isdeveloped in pumping oil, as the pump receives fluid through inlet 28and discharges it through restricted outlet 29. All parts of the pumpare responsive to the rotation of the drill pipe except rotor 32, whichis responsive to the torque developed in pumping oil through the pump.If there is a difl'erential speed of rotation between hit F9 and drillpipe l2, oil will be pumped. In the practice of my invention, therotational speed of bit l9 and the volume of oil circulated by the pumpare functions of the weight which is placed upon the bit. Furthermore,the speed of the bit varies inversely as the hardness of the formation,

whereas the volume of oil circulated varies di-- rectly as the hardnessof the formation. In coring a soft formation, bit I9 will rotate morerapidly than it will in coring a hard formation, while the rate of fluidcirculation in coring a soft formation will be less than in coring ahard formation. This feature of my invention climinates washing away the'soft portions of a formation core by high velocity fluid.

In describing a second embodiment of my invention, I have designatedlike parts by the same reference numerals. By referring to Figure 2, itwill be noted that in this embodiment bit i9 is bored to receiveandsupport core barrel I9 and is threadedly attached to an outer member43 which bears at the top against drill pipe l2. The top of the outermember is provided with a spider 44 by which the member is secured toshaft 33. A plurality of spacing members 45 are positioned'in annularspace I! to align core barrel I8, which may remain stationary or rotateindependently of bitl9. In addition to core retical to the firstembodiment.

"tational speed ofthe bit and the volume of oil taining means 38, asecond pair of core catchers 46 may be provided in core 'barrel l8 toaid in retrieving the core. The top ofthe core barrel has a conduit 41which establishes communication between the top of the core barrel andannular space 24 and through which the pressures" within the core barreland the annular space'are equalized. It will be noted that a packinggland 48 is placed'around conduit 41 in the top of the core barrel. Thepacking permits rotation of the cor'e'barrel and prevents thecirculating oil from entering the corebarrel from space H.

sage in said means; a fluid passage in said means communicatingwith thepump outlet; arecepy tacle communicating with the core passage for Theoperation of this second embodiment is very similar to the operation of,the first. The

' .torque developed in pump 25 turns outer member 43 and bit IS. Thefluid circulation is iden- Similarly, the rocirculated are functions ofthe weight placed on the bit,

It is to be understood that the forms of my invention, herewith shownand described, are to be taken as preferred examples. of the same, and

that various changes in shape, size and arrangement of parts may beresorted to without departing from the spirit of my invention, or thescope of the subjoined claims.

I claim:

I. In coring apparatus, the combination comprising a conduit adapted tobe rotated in a well bore; a pump including a casing secured to androtatable with the conduit and a rotor in the casing; core cutting andretaining means con--- nected to the rotor and adapted to engage thebottom of the well bore; and liquid supplied to the pump, whereby, uponrotation of the conduit and the pump casing, the said means will berotated against the resistance of its contact with the bottom of thewell bore.

2. In coring apparatus, the combination comprising a drill stem adaptedto be'rotated in a bore hole; a pump including a casing secured to thedrill stem and rotatable therewith, an inlet, an outlet, and a rotorinthe casing; a coring tool connected to the rotor and adapted to engageagainst the receiving and retaining core material, and liquid suppliedto the pump through the inlet thereof,

whereby upon rotation of the drill stem and the pump casing, the coredrill means will be rotated tom of the bore hole.

' 5. In coring apparatus, the combination comprising a drill stemadapted to be rotated in 'a borehole; a positive, displacement rotarypump I including a casing within the drill stem and secured thereto soas to rotate therewith, said casing forming a partition across theinterior of the drill stem, an inlet establishing communication betweenthe casing and the portion of the drill stem above the casing,anoutletestablishing communication between thecasing and the portion ofthe drill stem below the casing, and a rotor in the casing; acoring toolrotatably coupled to the lower. end ,of the drill stem and connected tothe pump rotor so as to rotate therewith, said coring tool being adaptedto engage the bottom of 1 the bore hole; and liquid supplied to the pumpcasing through the inlet thereof,

whereby, upon rotation of the drill stem and .the pump casing, thecoring tool will be rotated against the resistance of its contact withthe bottom of the bore hole.

6. In coring apparatus, the combination com-1 prising a conduit adaptedto be rotated in a bore hole, a positive displacement rotary pump in-'cluding a casing secured to the conduit and rotatable therewith, saidcasing forming a partition across the interior of the conduit, an inletI communicating with thecasing and the portion the bottom of the borehole; a passage in the coring tool communicating with the pump outlet;and liquid supplied to the pump through the inlet thereof, whereby, uponrotation of the drill stem and the pump casing, the coring tool will berotated against the resistance ofits contact with the bottom of the borehole.

3. In coring apparatus, the combination comprising a' drill stem adaptedto be rotated in a bore hole; a pump includinga casing secured to thedrill stem and rotatable therewith, an inlet,

an outlet, and a rotor in the casing; a coring tool connected to therotor and adapted to' en gage the bottom of'the bore hole;.said coringtool including rotary core cutting means, core receiving means, and apassage communicating with the pump outlet; and liquid supplied to thepump through the inlet thereof, whereby, upon rotation of the drill stemand the pump casing, 6 the coring tool will be rotated against the,re-,

sistance of it's contact with the bottom of the bore hole.

4. In coring apparatus, the combination comprising a drill stem adaptedto be rotated in a bore hole; a pump including'a casing secured to anoutlet, and a rotor in the casing; core drill means connected to therotorand adapted to engage the bottom of the bore hole; a core pasthedrill stem and rotatable therewith, an inlet,

of the conduit thereabove, an outlet communicating with the casing andthe portion of the conduit therebelow, and a rotor in the casing, acoring too1 rotatably'coupled to the 7 lower end oi the conduit andincluding a core drill connected to the pump rotor so 'asto rotatetherewith and adapted to engage the bottom of the bore hole,

a fluid passage extending through the core drill and communicating withthe pump outlet, a core receiving receptacle, and a core passage in thecore drill communicating with said receptacle;- and liquid supplied tothe pump casing through the inlet thereof, whereby, upon rotation of theconduit and the pump casing, the core drill will be rotated against theresistance of its contact with the bottom of the bore hole.

'7. In coring apparatus, the combination comprising a conduit adapted tobe rotated in abor'e hole, a positive displacement rotarypump includinga casing secured to the conduit and rotatable therewith, said casingforming a partition across the interior of the conduit, an inletcommunicating with the casing and the portion r of the conduitthereabove,an outlet communicata core receiving receptacle disposedwithin the conduit and spaced therefrom to form an annular passagetherewith communicating with the pump outlet and the fluid passageandpositioned intermediate the pump casing and the core drill, and acorepassage in the core drill communicating with said receptacle: aridliquidsupplied to the sistarice of its contact with the bot-' pump casingthrough the inlet thereof, whereby, upon rotation of the conduit and thepump casing, the core drill will be rotated-against the resistance ofits contact with the bottom ofthe bore hole.

8. In coring apparatus, the combination comprising a first conduitadapted to be rotated in a well bore; a second conduit extending belowthe nected to the second conduit; a coring tool connected to the secondconduit and adapted to engage the bottom of the bore hole; and liquidsupplied to the pump casing through the inlet, whereby, upon rotation ofthe first conduit and the pump casing, the second conduit and the coringtool will be rotated against the resistance of its contact with thebottom of the well bore.

9. In coring apparatus, the combination comprising a first conduitadapted to be rotated in a well bore; a second conduit extending belowthe first conduit and rotatable with respect thereto, said conduitsbeing in communication;' a pump including a casing forming a partitionacross'the first conduit and secured thereto so as to rotate therewith,an inlet'establishing communication between the casing and the portionof the first conduit thereabove, an outlet establishing com-'.munication between the casing and the second duit and adapted-toengage the bottom of the bore hole, a fluid passage extending throughthe core drill and communicating with the pump outlet,

a core receiving receptacle, and a core passage in the core drillcommunicating with said receptacle; and liquid supplied to the pumpcasing through the inlet thereof, whereby, upon rotation of the firstconduit and the pumpcasing, thesecond conduit and the core drill will berotated against the resistance of its contact with the bottom of thewell bore. 5

10. In coring apparatus, the combination comprising a first conduitadapted to be rotated in a well bore; a second conduit extending belowthe first conduit and rotatable with respect thereto, said conduitsbeing in communication; a pump including a casing forming a partitionacross the first conduit and secured thereto so as to rotate therewith,an inlet establishing communication between the casing and the portionof the first conduit thereabove, an outlet establishing communicationbetweenthe casing and the second conduit, and a rotor in the casingfixedly connected to the sec-ondconduit; a coring tool includ- 'ing acore drill connected to the second conduit and adapted to engage thebottom of the bore hole, a fluid passage extending through the coredrill, a core receiving receptacle within the second conduit and spacedtherefrom to form an annular passage therewith communicating with thepump outlet and the fluid. passage and positioned intermediate the pumpcasing and the core drill, and a core passage in the core drillcommunicating with said receptacle; and liquid supplied to the pumpcasing through the inlet thereof, whereby, upon rotation of the firstconduit and the pump casing, the second conduit and the core drill willbe rotated against the resistance of its contact with the bottom of thewell bore.

WILBUR J. CRITES.

